Walter



Patented Dec. 9, 193

unnan WALTER TAUSSIG, OF FRANKFORT-ON-THE-MAIN, GERMANY, ASSIGNOR TO DURANJD @a HUGUENIN, OF BASEL, SWITZERLAND, A CORPORATION OF SWITZERLAND PROCESS FOR PRINTING WOOL WITH ESTER SALTS F LEUfiQ CQMPOUNDS VAT DYESTUFFS No Drawing. Application filed October 12, 1928, Serial No. 312,209, and in Germany Qctober 10, 1927.

My invention relates to a process for printing wool with ester salts of leuco-compounds of vat dyestuffs. These ester salts well known in the practice are applied in a wide extent for printing cotton and for dyeing wool. But for printing wool they could not be used hitherto because there was not known a suitable oxidizing agent which develops sufficiently the dyeing of the ester salt but does not stain the nonprinted part of the woolen fabric. I have now found that ester salts of leuco"- compounds of vat dyestufi's when printed on wool are developed in an excellent fastness, without staining the white "part of the woolen fabric, by means of solutions of persulfates mixed with strong acids as sulfuric or hydrochloric acid. A special advantage of my present process consists in the fact that the print pastes contain only a thickening agent besides the solution of ester salts of the leuco-compounds of vat dyestufi's'.

Only when such ester salts of leuco-compounds of vat dyestuffs are applied which are too difficult to be reoxidized, some persulfate is advantageously admixed already to the printing color.

In order to further illustrate my invention the following examples are given, the parts being by weight and all temperatures in Centigrade degrees. But I wish to be understood that I am not limited to the particular conditions nor to the specific products mentioned therein.

Example 1 6.6'-diethoxy-thioindigo, parts 70 5.7.6 -trichIoro-indigo, parts 50 5.7.5.7 -tetrabromo-indigo, parts 80' The dyestufi prepared according to Exampletl of the German Patent No. 241,997, par s Parts 0! water 330 350 320 275 Parts of British gum 1:1 600 600 600 600 Parts 1000 1000 1000 1000 After having been printed and dried the goods are steamed for about half an hour in Emample 2 Woolen material is printed with the following print-paste:

Sulfuric acid ester salt of the leuco-compound of 4.4-dichloro-6.6'-dimethyl thioindigo,

parts Parts of water Parts of British gum 1: 1 Parts of potassium persulfate Parts 1000 The printed fabric is developed as described in Example 1.

I claim 1. A process which comprises printing woolen fabrics with a printing paste containing a thickening agent and a solution of an ester-salt of a leuco compound of a vet dyestuff, drying and steaming the printed fabrics and treating them with a strong mineral acid in combination with a persulfate as oxidizing agent, this latter being admixed at any stage of the process and being incapable of staining the white parts of the woolen fabrics.

2. A rocess which comprises printing woolen abrics with a printing paste containing a thickening agent and a solution of an ester salt of a leuco vat dyestufif, drying and steaming the printed fabrics and treating them with a solution containing a strong mineral acid and a persulfate as oxidizing agent incapable of staining the white parts of the woolen fabrics.

3. A process which comprises printing woolen fabrics with a printing paste containing a thickening agent and a. solution of an ester salt of a leuco compound of a vat dyestulf, drying and steaming the printed fabrics and treating them with a solution containing 00 hydrochloric acid and a persulfate as oxidizing agent incapable of staining the white parts of the woolen fabrics.

4. A process which comprises printing woolen fabrics with a printing paste containing a thickening agent and a solution of an ester salt of a leuco compound of a vat dyestuff, drying and steaming the printed fabrics. and treating them with a solution containing per liter from 12 to parts of hydrochloric acid 20 B. and from 10 to 20 parts of potassium persulfate, at a temperature of 50 to 70 C.

In testimony whereof, I afiix my signature.

WALTER TAUSSIG. 

